1. Field of the Invention
The present invention relates to a portable direct sensor attachment system and more particularly pertains to allowing a user to evaluate and detect flaws in railroad tracks.
2. Description of the Prior Art
The use of railroad track inspection systems is known in the prior art. More specifically, railroad track inspection systems previously devised and utilized for the purpose of detecting flaws in railroad tracks are known to consist basically of familiar, expected, and obvious structural configurations, notwithstanding the myriad of designs encompassed by the crowded prior art which has been developed for the fulfillment of countless objectives and requirements.
By way of example, U.S. Pat. No. 6,262,572 issued Jul. 17, 2001, to Wojnarowski et al. discloses an electromagnetic system for railroad track crack detection and traction enhancement. U.S. Pat. No. 5,386,727 issued Feb. 7, 1995, to Earle discloses a dynamic rail longitudinal stress measuring system. Finally, U.S. Pat. No. 4,468,966 issued Sep. 4, 1984 to Bradshaw discloses a railroad track inspection car.
While these devices fulfill their respective, particular objectives and requirements, the aforementioned patents do not describe a portable direct sensor attachment system that allows allowing a user to evaluate and detect flaws in railroad tracks.
In this respect, the portable direct sensor attachment system according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of allowing a user to evaluate and detect flaws in railroad tracks.
Therefore, it can be appreciated that there exists a continuing need for a new and improved portable direct sensor attachment system which can be used for allowing a user to evaluate and detect flaws in railroad tracks. In this regard, the present invention substantially fulfills this need.
With greater specificity, the sensing devices, sensors, for the nondestructive testing of railroad rail and similar structures require that a sensor be placed and maintained in close proximity or in contact with the surface of the rail. These sensors must also be maintained in precise longitudinal and lateral alignment with respect to the rail to implement specific inspection procedures. The sensors or sensor carriage assembly is normally attached to the frame or body of a rail bound vehicle such as a highway/railway vehicle that can be driven along the rail. Alternatively, the sensors or sensor carriage may be assembled into an independent cart that is pulled along the rail by a rail-bound vehicle such as a locomotive or a highway/railway vehicle or carried between the wheels of such a vehicle.
In addition, means must be provided to ensure that the sensor or sensor carriage is protected from obstacles and anomalies in the rail surface geometries such as misalignment and gaps in the rail. When the sensor or the sensor carriage is attached to the frame of body of the host vehicle, the attachment mechanism must compensate for the vehicle suspension mechanisms and vehicle load conditions to provide the proximity, alignment and protection requirements of the sensors. When the sensor or sensor carriage is integrated into an independent cart that is pulled behind a rail-bound vehicle or carried between the wheels of the vehicle, the mechanism is bulky and complex. Size, weight and handling issues make placement and removal from the track and overall stability during movement over the rail.
In the method and apparatus of attachment of the present invention, the sensor or sensor carriage is attached directly to the wheels of the host vehicle that are used to guide the rail-bound vehicle on the rail thereby eliminating the effects of the suspension and related mechanism when attached to the chassis of the inspection vehicle or eliminating the need for an independent cart to be attached in some way to a rail-bound vehicle. The design facilitates rapid removal and egress or entrance of the inspection vehicle at any level crossing.
The present invention is a significant simplification over current rail inspection deployment mechanisms. Its simplicity makes the inspection capability portable and conveniently deployable on conventional rail maintenance and visual inspection vehicles that are in widespread use in railway systems and eliminates the need for costly suspension devices or special carts that are pulled behind or otherwise integrated into such vehicles. It is light in weight and can be removed easily from one vehicle and moved, carried by one person and mounted on another vehicle thereby readily providing an inspection capability on a fleet of vehicles.
In the case of electromagnetic acoustic transducers that must operate at a fixed minimum clearance above the rail surface, this device uses the magnetic force between the transducer and the rail to provide mechanical stability while facilitating precise setting of clearance distances as required.
This invention generally relates to nondestructive testing of railroad rails and further relates to an apparatus and method for maintaining a nondestructive testing sensor or array of sensors in close proximity or contact with the rail, in longitudinal and lateral alignment with the rail and follows the anomalies in the vertical rail surface profile to protect the sensor(s) from damage from such anomalies.
High reliability is essential in the operation of a railroad system to assure the safety of the public and passengers and the safe and efficient movement of goods. U.S. railways carry high and increasingly higher freight tonnages. A key high-performance element in the system is the rail. These operational factors in diverse climatic environments present several challenges to rail integrity. As a load-bearing component, rail requires a high level of materials integrity that depends on quality control of rail manufacturing and in-service inspection of rail. Over the decades of experience with inspection of rail for internal defects both ultrasonics and magnetic flux leakage have been used. Of these, ultrasonics has become the method of choice because it generates more information than magnetic flux leakage about a wider range of defects.
The ultrasonic or magnetic flux leakages or other sensor is carried on a host vehicle and is generally attached to the frame of body of the host vehicle through a carriage mechanism designed to maintain proximity or contact with the rail, alignment and protection from rail surface anomalies. In these current configurations, the attachment mechanism between the vehicle chassis and the rail is complex because it has to follow not only the rail but also the vehicle movements through the suspension system. The behavior of the vehicle chassis is not consistent and depends on such factors as the vehicle payload and its distribution. These compensations are provided through devices such as pantograph assemblies and mechanisms such as pneumatic and hydraulic as well as spring actuators and mechanical guide devices to provide the required positioning and protection. They are mounted on specialized vehicles, trailer assemblies or other complex mechanisms for rail inspection. This results in costly mechanisms and costly inspections with attendant low availability of inspection systems and lower frequency of inspection than would be desirable to maintain rail system reliability.
There is a need for a simpler mechanism to lower the cost of inspection equipment, to lower the cost of inspection and provide more frequent and reliable inspection. This requirement applies to conventional ultrasonic testing and other methods used for nondestructive testing of rail but are particularly required with the use of electromagnetic acoustic transducers used to introduce ultrasonic waves. In this case, it may be required to maintain a certain lift-off between the sensor and the rail.